The present invention relates to an exhaust gas diffuser for use with an exhaust system of an internal combustion engine and connected to the end of an exhaust pipe principally for the purpose of reducing the temperature of the exhaust gases discharged from the exhaust pipe to the atmosphere.
In recent years there has been a tendency for the temperature of the exhaust gases discharged from the exhaust pipe of an automobile engine to become hotter due to techniques used for exhaust gas purification, and because of this thermal problems such as burning and fire caused by hot exhaust gases discharged from an automobile engine have now become a more serious problem. As a means for reducing the temperature of the gases discharged from an automobile engine, an exhaust gas diffuser is known which is adapted to be mounted to the discharge end of an exhaust pipe so that hot exhaust gases are mixed with cold atmospheric air within the diffuser before being discharged to the atmosphere. Such an exhaust gas diffuser typically comprises a tubular body defining a passage therein which has a cross-sectional area larger than the internal cross-sectional area of the corresponding exhaust pipe, a connecting port provided at an axial end of the tubular body for connection with the exhaust pipe, an external air inlet port provided adjacent to the connecting port at an axial end of the tubular body, and an exhaust port provided at the other axial end of the tubular body, wherein it is intended that the flow of exhaust gases discharged from the connecting port into the passage defined by the tubular body causes entrainment of external atmospheric air into the passage through the external air inlet port due to the well-known Venturi effect so that the exhaust gases discharged from the exhaust pipe are mixed with external atmospheric air before they are discharged from the exhaust port of the tubular body. However in this conventional type of exhaust gas diffuser the entrainment of external atmospheric air into the tubular body through said external air inlet port does not actually effectively occur and exhaust gases are still discharged from the exhaust port of the tubular body without being sufficiently mixed with atmospheric air and thus without their temperature being sufficiently lowered.